Biography

Joseph Henry was the son of a Swedish working man. He was born in 1797 in Albany, New York, but moved to live with his grandmother 40 miles outside of Albany. His original idea was to forgo college, but some of his friends persuaded him to go to Albany Academy. He had always been interested in science and he was offered free tuition, so he said yes. He quickly rose to the top of his classes and was soon assisting the teachers. After only a bit, he gave up college and started to teach it. In addition to natural philosophy, Henry taught chemistry, geology, mineralogy, astronomy, and architecture.

Here, despite a teaching schedule that occupied seven hours each day, was able to do most of his important scientific studies. After experimenting and tinkering, Henry became very interested in magnetism. This led him to experiment with electromagnetism. Henry was the first scientist to wind metal wires around an iron core to obtain powerful electromagnets. Henry observed a large spark that was generated when the circuit was broken, and he deduced the property known as self-inductance. Henry also found that self-induction is greatly affected by the placement of the circuit, especially how much the wire is coiled. He also discovered how to make non-inductive bindings by folding the wire back on itself

While Henry was doing these experiments, Michael Faraday did similar work in England. Henry was too slow to publish his results at the time of completion, and he was unaware of Faraday's work. The result is that today Faraday is recognized as the discoverer of mutual inductance while Henry is credited with the discovery of self-inductance

Henry was one of the first members of the National Academy of Sciences and served as its second president. He was also a trustee of Princeton and president of the American Association for the Advancement of Science. When he died in 1878 his funeral was attended by the president of the United States with his cabinet, the chief justice and associate justices of the Supreme Court, by many members of both houses of Congress